You found your soul mate; now you just need to find an engagement ring that she’ll love for, oh, the rest of her life. There’s bafflingly little useful advice out there about buying an engagement ring. So we’ve assembled some hard-won wisdom that will help you get what you want—which, really, is all about what she wants—without getting suckered.

1. This Is Gonna Sting a Little

You’ll hear that you should spend two to three months’ salary on a ring, but that’s pre-recession talk. Be realistic: Start with four to six weeks’ worth of paychecks, and be prepared to drop a little extra if it’ll get you perfection.

2. Act Like a Cat Burglar

Don’t guess at her size—steal one of her rings to have it sized by a jeweler. While you’re in her jewelry box, take a few cellphone shots so you can remember what she likes.

3. Turn Her Friends Into Accomplices

Ask her pals (the ones who can keep a secret) if she’s dropped any hints—the type of metal, the cut of the stone, a designer she likes. Because she has.

4. Think of Yourself, Just This Once

She might want her wedding band to match her engagement ring—and some couples like their wedding bands to match, too. In other words: Know that if you get her a rose-gold band, you might also end up wearing rose gold.

5. Know the Rules of the Rock

You can get a quick education online about how gemologists grade stones, but after that, you need guidelines: For a diamond, avoid any color grade below H (too yellow) or any cut grade below Very Good (not enough sparkle). We’d choose a better cut and clearer color over more carats, but if she’s expecting a boulder, your choice is made for you.

6. Go Beyond the White Diamond

These days it’s cool to put some color on her ring finger; black diamonds, yellow diamonds, emeralds, and sapphires are all fair game as center or accent stones.

Just remember to nail the kind of ring that she really likes. So, are you now ready to pop the question? Were these tips helpful?